package com.bupt.core.base.util;

import java.security.MessageDigest;   

/**  
 * cipher user password by MD5  
 *   
 * @author Administrator  
 * @date 2011-2-11  
 */  
public class CipherUtil {   
  
    private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",   
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };   
  
    /**  
     * cipher password  
     *   
     * @param inputString  
     * @return  
     */  
    public static String generatePassword(String inputString) {   
        return encodeByMD5(inputString);   
    }   
  
    /**  
     * validate password  
     *   
     * @param password  
     * @param inputString  
     * @return  
     */  
    public static boolean validatePassword(String password, String inputString) {   
        if (password.equals(encodeByMD5(inputString))) {   
            return true;   
        } else {   
            return false;   
        }   
    }   
  
    /**  
     * encode  
     *   
     * @param originString  
     * @return  
     */  
    private static String encodeByMD5(String originString) {   
        if (originString != null) {   
            try {   
                MessageDigest md = MessageDigest.getInstance("MD5");  
                byte[] results = md.digest(originString.getBytes());   
                String resultString = byteArrayToHexString(results);   
                return resultString.toUpperCase();   
            } catch (Exception ex) {   
                ex.printStackTrace();   
            }   
        }   
        return null;   
    }   
  
    /**  
     * change the Byte[] to hex string  
     *   
     * @param b  
     * @return  
     */  
    private static String byteArrayToHexString(byte[] b) {   
        StringBuffer resultSb = new StringBuffer();   
        for (int i = 0; i < b.length; i++) {   
            resultSb.append(byteToHexString(b[i]));   
        }   
        return resultSb.toString();   
    }   
  
    /**  
     * change a byte to hex string  
     *   
     * @param b  
     * @return  
     */  
    private static String byteToHexString(byte b) {   
        int n = b;   
        if (n < 0)   
            n = 256 + n;   
        int d1 = n / 16;   
        int d2 = n % 16;   
        return hexDigits[d1] + hexDigits[d2];   
    }   
  
    public static void main(String[] args) {   
        String pwd1 = "litong8899litong8899";   
        String pwd2 = "";   
        System.out.println("未加密的密码:" + pwd1);   
        // 将admin加密   
        pwd2 = CipherUtil.generatePassword(pwd1);   
        System.out.println("加密后的密码:" + pwd2);   
  
        System.out.print("验证密码是否正确:");   
        if (CipherUtil.validatePassword(pwd2, pwd1)) {   
            System.out.println("正确");   
        } else {   
            System.out.println("错误");   
        }
        
    }   
  
}  